Skeletal plating system

ABSTRACT

The present invention is directed to (1) a plating system having multiple and single locking mechanisms for general skeletal use other than in the anterior cervical spine; (2) an orthopedic plating system that permits a pair of bone screws to be inserted into a bone in a crossed over orientation and locked to the plate; (3) a segmentable plating system which can be made to a selected length by the surgeon; and (4) a combination screw-lock-plating system for allowing and/or causing intersegmental compression of bone portions.

RELATED APPLICATIONS

[0001] This application is a continuation of application Ser. No.10/098,991, filed Mar. 15, 2002; which is a divisional of applicationSer. No. 09/669,912, filed Sep. 26, 2000, now U.S. Pat. No. 6,383,186;which is a divisional of application Ser. No. 09/022,344, filed Feb. 11,1998, now U.S. Pat. No. 6,139,550; which claims the benefit ofprovisional application Ser. No. 60/037,139, filed Feb. 11, 1997; all ofwhich are incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates generally to skeletal plate systemsfor aligning and maintaining bone portions of the same bone or ofdifferent bones in a selected spatial relationship for healing or fusionof the bone portions, respectively. In particular, the present inventionrelates to skeletal plating systems comprising a plate that is flatand/or convex over a substantial portion of the lower surface of theplate along the longitudinal axis of the plate, bone screws, and locksfor locking the bone screws to the plate; to segmentable plates;crossing screw plates; and combination bone screw-lock-plate systemspermitting or causing, intersegmental bone compression and/orshortening.

[0004] 2. Description of the Related Art

[0005] It is current practice in orthopedic surgery to use platingsystems for joining portions of a broken bone, or for fusion of portionsof separate bones. Such systems are composed essentially of plates andscrews for aligning and holding the bone portions in a desired positionrelative to one another. Plating systems have usefulness in the spine,and have general skeletal use on the flat bones, such as the scapula andthe pelvis by way of example, and for use on tubular bones, such as thehumerus, ulna, radius, femur, and tibia by way of example.

[0006] Problems associated with such plating systems have includedhardware breakage, hardware loosening, inability to gain adequatefixation, and distraction pseudoarthrosis where the plate will not allowthe bone portions to come together over time resulting in a failure toget solid bone healing. These occurrences may cause problems, beassociated with surgical failure, and require further surgicalprocedures to repair the damage, remove the failed hardware, and/or toreattempt skeletal stabilization.

[0007] Plates are usually provided to the surgeon for use in sets havinga range of sizes so as to provide for such features as biologicalvariability in size, the numbers of segments to be joined, and thelength of the portions of bone to be joined. By way of example, it wouldbe common for a plating system for use on the anterior cervical spineand for joining from two to five vertebrae to comprise of from forty tosixty plates. This requires manufacturers to make a large number ofdifferent plates, resulting in increased manufacturing costs andinventory costs and increased costs for hospitals to stock large numbersof plates. Further, in the event that a plate is used and another of itskind is needed before it can be replaced, the ability to provide to apatient the best care could be compromised.

[0008] Known plating systems additionally experience problems inconnection with those procedures where bone grafts are placed betweenvertebral bodies to achieve an interbody fusion which heals by a processcalled “creeping substitution”. In this process, dead bone at theinterfaces between the graft and the adjacent vertebra is removed by thebody, as a prelude to the new growth of bone forming cells and thedeposition of new bone. While the plates allow for proper alignment ofthe vertebrae and their rigid fixation, they can therefore, at the sametime unfortunately, hold the vertebrae apart while the resorption phaseof the creeping substitution process forms gaps in the bone at thefusion site with the result that the desired fusion does not occur. Suchfailure in an attempted fusion is known as pseudoarthrosis. A similarphenomenon occurs at the interface of a fractured bone's fragments andis known as non-union. When such a failure occurs, the hardware itselfwill usually break or become loosened over time requiring furthersurgery to remove the broken hardware and to again attempt fusion orfracture repair.

[0009] Based on a consideration of the features of all of the knownplating systems, there remains a need for an improved plating systemhaving the following combination of features:

[0010] 1) The plate and screws should be sufficiently strong to performtheir intended function without mechanical failure;

[0011] 2) The hardware, and specifically the screws, should be capableof achieving adequate purchase into the bone;

[0012] 3) Means should be provided for locking each and every bone screwto the plate, and the locking means should be of sufficient size andstrength to reliably perform its intended functions;

[0013] 4) Bone screw locking means should preferably be retainable bythe plate prior to bone screw insertion, or should be reliablyattachable to a driver to prevent any small parts from becoming loose inthe wound;

[0014] 5) Bone screw orientation should be provided to create maximumscrew purchase into bone and high resistance from being dislodged fromthe bone;

[0015] 6) An improved and lower cost of production method for themanufacturer of medical plates should be provided;

[0016] 7) A plate system should be provided for use in various sizes ofpatients which can be easily made to a selected length by a surgeon tofit the desired application in order to substantially reduce the numberof plates required; and

[0017] 8) Bone screw and plating system should be provided that preventholding apart of bone portions during the process of creepingsubstitution and causes, or permits, or both causes and permits the boneportions to move toward each other to permit and promote the fusion orhealing of the bone portions.

SUMMARY OF THE INVENTION

[0018] The present invention meets the above stated needs by providingvarious embodiments which are combinable, and may all be utilizable inthe same plating system, such embodiments include (1) a skeletal platingsystem comprising a plate, that is flat over a substantial portion ofits lower surface along the longitudinal axis of the plate and/or thathas a lower surface that is convex curved along a substantial portion ofthe longitudinal axis of the plate, bone screws, and locks for lockingthe bone screws to the plate for skeletal use; (2) a skeletal platingsystem that permits a pair of bone screws to be inserted into a boneportion in a crossed over orientation and locked in place to the plate;(3) a segmentable skeletal plating system constructed so as to beselected for length by the surgeon; and (4) a combinationscrew-lock-plating system capable of allowing or urging bone portionstogether.

[0019] 1. General Use Skeletal Plating-System

[0020] a. Multiple Lock System

[0021] The plating system of a first embodiment of the present inventioncomprises a general use skeletal plate having a bottom surface forplacement against bone portions, wherein a substantial portion of thebottom surface of the plate is either flat or convex along thelongitudinal axis of the plate. It is appreciated that a lesser portionof the lower surface of the plate may be otherwise shaped. The plate ofthe present invention has a plurality of bone screw receiving holeswhich extend through the plate, from the upper surface to the lowersurface. The plate and its component parts, may be made of any implantquality material suitable for this purpose and suitable for use in thehuman body, such as, but not limited to, titanium or its alloys. Theplate and/or the associated components may be made of a bioresorbablematerial and may comprise or be coated at least in part with fusionpromoting chemical substances, such as bone morphogenetic proteins andthe like.

[0022] Bone screws are each insertable into a respective bone screwreceiving hole for attaching the plate to bone. A locking element,preferably, but not necessarily, in the form of a screw, is engageablein the locking screw hole of the plate and has a head formed to lock atleast two of the bone screws to the plate. In the preferred embodiment,the locking elements are pre-installed prior to use by the surgeon in amanner so as to not impede installation of the bone screws into the bonescrew receiving holes.

[0023] As a result, the problems previously associated with the lockingscrews of the type applied after the insertion of the bone screws,including the problems of instrumentation to position and deliver to theplate the locking means, backing out, breakage, stripping andmisthreading associated with the prior art more delicate locking screwsresembling “watchmaker's parts”, are eliminated.

[0024] b. Single-Lock System

[0025] The plating system of the second embodiment of the presentinvention comprises a single-lock plate for skeletal use having a bottomsurface for placement against bone portions, wherein a substantialportion of the bottom surface of the plate is either flat or convexalong the longitudinal axis of the plate. The single-lock plate has alocking element that fits within a bone screw receiving hole or into arecess overlapping a bone screw receiving hole to lock a respective oneof the bone screws in place. According to this second embodiment of theinvention, each of the bone screws is locked to the plate by means of anindividual locking element which covers at least a portion of the bonescrew. Since in the preferred embodiment of the single-lock plate, noother holes need be formed in the plate to attach the locking elementsto the plate, the plate remains quite strong, or alternatively can bemade thinner or narrower while keeping the requisite strength for theparticular application.

[0026] The locking elements can be in many forms to achieve theirintended purpose, such as, but not limited to, screws, threaded caps,rivets, set screws, projecting elements, and the like.

[0027] In common, neither the single-lock nor the multiple lock platingsystem requires that the head of the bone screw be hollow, as per someprior known plating systems. It will be appreciated that bone screws areweakened when their heads or head and neck portions are hollow so as toaccommodate a second screw at least in part, if not wholly within.

[0028] 2. Crossing Screw Plating System

[0029] In a further embodiment of the present invention, combinable inapplication with either the multiple lock or the single-lock systems andother novel features herein taught, a plate provides for the crossingover of the shafts of at least a pair of bone screws within a boneportion. A crossed orientation of the screws within the bone provides amore secure engagement of the plate to the bone to which it is to beapplied because longer screws may be used and because an area of bone iswedged and trapped between the screws as compared to plates which do notallow paired screws to cross. The use of further screws crossed and/ornot crossed in combination with the crossed screw pair can be utilizedto trap a still larger section of bone. The plate of the presentinvention may have multiple bone screw receiving bores (with fixedcentral longitudinal axes) in which the bores are oriented in astaggered configuration, such that the center points of each of thepaired bone screw hole receiving bores are on different transverse linesto permit at least a pair of bone screws to be inserted in acrossed-over configuration within a bone portion. Preferably, the screwbores have defined longitudinal axes in the transverse plane of theplate though the screws may be capable of a variation in positioning aswill subsequently be described. In the preferred embodiment, theincluded angle formed by the shafts of the crossed screws is between 25to 90 degrees. For spinal use, by way of example, the paired screws arestaggered, but are still alignable within the same vertebra so as to bediagonally crossed within that same vertebra and preferably crossedwithin the posterior two thirds of the vertebral body.

[0030] 3. Segmentable Plating System

[0031] In a further embodiment of the present invention a segmentableplating system is disclosed combinable with the multiple lock andsingle-lock plating system and the crossing screw teaching, as well ascombinable with other novel features herein taught. The segmentableplating system provides a single plate, or a limited set of plates, foraligning and maintaining bone portions in selected spatial relationshipin which the plates are manufactured so as to be strong in use, butseparable into shorter lengths by the surgeon as needed, therebyeliminating the need to stock a multitude of plate lengths.

[0032] By way of example, for application in the spine, an embodiment ofthe segmentable plating system of the present invention comprises aplate that is capable of spanning multiple segments of a cervical spineand has predetermined separation zones. The separation zones may bepositioned in a segmentable plate such that when a portion of thesegmentable plate would be applied to the vertebrae, the remainingseparation zones in the plate, if any, would be supported by anunderlying vertebrae. In use, the surgeon would determine theappropriate plate length needed and if the length needed was less thanthe length of the provided plate, the surgeon would remove the unneededportion of the plate at the appropriate separation zone. By way ofexample, this procedure may be easily performed when the plate is madeof titanium or one of its alloys, as the properties of titanium are suchthat when the plate is bent and then returned to its original position,a clean separation is made at the bend. The parts of the segmentableplates that are being separated can be held to either side of theseparation zone to ensure that a precise separation is effected. Theseparation zones of the segmentable plate, by way of example, maycomprise of the plate being scored along its upper, lower, or both upperand lower surfaces. The depth of such scores being dependent on thethickness of the plate, and being sufficient to create surface notchingsand a path of least resistance for the plate separation, and yet oflimited depth and shape, so as to not weaken the plate so as to renderit less than sufficiently strong for its intended use.

[0033] By way of example, for application to the anterior aspect of thecervical spine four segmentable plates each having generally a similarlength for example sufficient to span five vertebrae (a length of from80 to 120 mm), and each having different spacings between pairs of bonescrew holes could comprise a complete set of plates allowing a surgeonto have all lengths and hole spacings needed to fuse from two to fivevertebrae. While the described plates may be separable into a multitudeof usable portions, because of regulatory issues involving theidentification of each implant with a distinct and singular implantidentification number for tracking purposes it may be desirable toconfigure the plates of the present invention such that each plate willyield only one usable portion, such as is taught in the presentinvention.

[0034] The segmentable plating system of the present invention also hasapplication in reconstructive surgery. For example, during repair of abroken eye socket, the segmentable plating system of the presentinvention can be used to align and maintain the broken bone portions incorrect spatial relationship. The curved characteristic of an eye socketwould require the plate used to repair the socket to match thecurvature. The segmentable plate of the present invention may be made ofa malleable metal, with the malleability of the plate being enhanced bythe segmentation of the plate, such that it can more easily be contouredby the surgeon to the appropriate curvature. The correct length of thesegmentable plate can also be easily obtained by the surgeon as alreadydescribed. It should be noted that if for example surgical titaniumalloy is selected for the plate material, then the separation zonesallow the plate to be more easily bent, but without separating. Thepresent invention makes a virtue of the material property of that alloyin that it may be bent without damage, but fails with surprisinglylittle force if first bent and then bent back. Back bending is thereforeonly done for plate separation and is not needed for contouring whichrequires only primary bending.

[0035] The ability to separate a plate into segments also providessignificant advantages in the manufacturing process. By way of example,in the process of investment casting, a process commonly used to produceplates. The investment casting cost of material is minor relative to thelabor involved in the casting process for the production of each plateregardless of size. It is far more economical to cast one eight inchlong plate, which is later separable into four two inch long plates,than to make four two inch castings. If machining is included inproduction, as from bare stock or stamping or casting, that work can beautomated, but the placing of the piece into the machine and securing it(fixturing) generally requires hands on attention, is time consuming,and is a potential manufacturing bottleneck. An eight inch long plateyielding four two inch plates potentially separable at the end by themachine doing the machining, may be fixtured only once. In contrast, theprior art method of manufacturing would require each of the four twoinch long plates to be fixtured separately, one at a time. Therefore,the manufacturer can cast one long segmentable plate which can then beseparated in the later manufacturing stages to yield multiple plates atan overall lower cost. Similarly, if the plate were in the alternativeto be manufactured by machining from solid stock, great labor could besaved by fixturing and securing a single long plate that is laterseparable into multiple plates rather than having to fixture and secureeach of those plates individually.

[0036] 4. Combination Screw-Lock-Plating System Capable ofIntersegmentable Compression and Shortening

[0037] In a further alternative embodiment combinable with both thesingle-lock and multiple lock plate designs, the crossed screw teaching,and the segmentable plate teaching as well as other novel aspects of thepresent invention taught herein, three types of combinationscrew-lock-plate systems are taught, each capable of intersegmentableshortening and/or compression. Each of the taught systems is designed tocounteract and compensate for the lack of contact between bone portionsto be joined that may occur as a result of creeping substitutiondescribed above. The present invention will allow the vertebrae to movetoward an interposed bone graft, and each other if necessary, instead ofkeeping the vertebrae apart during the occurrence of the resorptionphase of the creeping substitution process. Unlike prior art “dynamic”and/or compression plating systems, the present invention may allow forthe preservation and/or enhancement of lordosis while otherwiserestricting the motion of the bone screws relative to the plate.

[0038] The three types of screw-plate-lock systems, which are themselvescombinable with one another, are as follows: (1) Passive Dynamic; (2)Self-Compressing; and (3) Active Dynamic and are described below.

[0039] a. Locked Passive Dynamic Plating System

[0040] As used in this description, the term “locked” means the screwsare locked to the plate and can not back out. The term “dynamic” meansthe screw is capable of movement even though it is locked within theplate to allow bone portions to move closer together. The term “passive”means motion of the screw relative to the plate is allowed, but notcaused.

[0041] The passive dynamic system allows a bone screw to move relativeto the plate even after being locked to the plate when a force ispresented against the screw. This system does not cause screw movement,but only allows for movement of the screw to occur and thus is a“passive” system. In a preferred embodiment, motion of the screwrelative to the plate is confined to but one direction, that directionpermitting bone portions to move closer to one another along thelongitudinal axis of the plate.

[0042] In the passive dynamic system, a plate having a screw holepassing through the top and bottom surfaces of the plate for receiving abone screw, may have a round opening at the top of the plate and mayhave a bottom opening that is oblong-shaped with a length greater thanthe diameter of a bone screw shaft locatable the screw hole when in use.The head of the bone screw is secured to the plate against backing outand generally against significant linear motion with a locking element,while the shaft of the bone screw is capable of angular motion relativeto the plate. The oblong-shaped bottom opening of the screw hole allowsthe shaft of the bone screw to travel relative to the plate while thebone screw head rotates. The movement of the screw is greatest at thedistal end of the screw, allowing for differential shortening of thebone portions being joined. For example, if such a plating system isapplied to the anterior aspect of the cervical spine, lordosis (a convexcurvature forward of the aligned vertebrae of the neck when viewed fromthe side) is enhanced when said passive movement occurs.

[0043] b. Self-Compressing Locking Plate System

[0044] In the self-compressing system, as a bone screw undergoes finaltightening, or as it is being locked to the plate with a locking elementthe bone screw is forced to move in one allowed and desired direction.The bone screw can not move back once it is locked to the plate by thelocking element. A purpose of the self-compressing system is to providea fixed and locked angle of the bone screw relative to the plate forproviding compression of bone portions to be joined, such as for examplethe cervical vertebrae adjacent a disc space, with movement of the bonescrew as it is seated to the plate, producing compression and lordosis.

[0045] Unlike prior screw systems, the screws are only allowed to movein one direction, that being the direction that would bring boneportions to be joined closer together by angular motion, rather than toproduce translational motion of a screw as a whole, without angularchange. This induction of a compressive load across bone portions to bejoined or fused, induces bone growth and when bone resorption occurs atthe interface of the bone portions to be joined, those bone portions areurged to move closer together, thus avoiding the formation of a gap soas to mitigate against non-union or pseudoarthrosis.

[0046] The self-compressing system may comprise a plate having a bonescrew receiving hole passing through the top and bottom surfaces of theplate with a top opening that is round and has a rounded seat. The bonescrew receiving hole has bottom opening that has a central longitudinalaxis that is offset from the central longitudinal axis of the topopening. The bone screw may have a partially rounded head which fitswithin the upper portion of the bone screw opening and permits movementof the screw head within the top opening in order to provide theappropriate angle for the bone screw shaft with respect to the plate asthe bone screw shaft passes through the bottom opening.

[0047] Further it is known in the art that compressive forces across thebone further induce bone growth and formation and the present inventionteaches novel ways of maintaining bone to bone contact, compressiveloading, and even a means for enhancing and increasing the compressiveload. A further benefit of the present invention can be appreciated byway of example in regard to use of the present invention on the anteriorcervical spine for spinal fusion.

[0048] c. Active Dynamic Locking Plating System

[0049] In the active dynamic system, a pre-load force is applied to abone screw such that while the screw may undergo no added motioninitially, there is a selective force applied to the screwhead and thescrew is capable of motion in only one direction, such that shouldresorption occur at the interfaces of the bone portions to be joinedthen the screw is not only free to move in that, and only thatdirection, but is also urged to do so as it moves to relieve the preloadforce. Features of these systems may be combined with each other.

[0050] By way of example only and not limitation, a plating system mayutilize bone screw holes that have a lower surface opening that isoblong and extends from the center aligned to the longitudinal axis ofthe bone screw receiving bore in a direction for which screw motion isdesired. A loading means such as a Bellville washer, lock washer, orother springing means is employed to bear upon the screw head when thescrew is locked within the plate from backing out. Such a system urgesthe bone portions together over time as resorption permits.

[0051] For any given use, (plate, screw, hole, and spring) it is simpleto determine correct resistance, that being an amount less than wouldbreak the bone to which the force is being applied. The Belville-typewasher can have a tab which fits into a recess formed within the topopening of the screw hole in order to facilitate proper orientation ofthe washer or the washer or spring means can be other than round so asto be directionally orientable when placed within the top opening of thescrew hole.

[0052] When features of these self compressing and active dynamicsystems are combined, such a system forces bone portions close upontightening and then both allows and urges such further motion, asresorption permits over time. The bone screw will only move further inthe pre-oriented direction if there is space available and if there isan opposing force present less than the pre-loaded force on the screw.

OBJECTS OF THE INVENTION

[0053] It is an object of the present invention to provide an improvedplating system which has the above described features and which avoidsmany of the shortcomings of previously known systems.

[0054] It is another object of the present invention to provide alocking mechanism where a plurality of bone screws used for attaching aplate to a bone portion can be easily and reliably locked in place atthe same time by a single operation, and wherein the locking mechanismsfor locking the bone screws may be pre-installed by the manufacturerprior to the insertion of the bone screws by the physician so that thephysician does not have to attach the locking mechanism to the plate asa separate procedure during the operation.

[0055] A further object of the invention is to provide plates which aretextured or otherwise treated to promote bone growth beneath the plate.

[0056] Yet another object of the invention is to provide a system inwhich the bone screws and locking mechanisms, when fully installed, havea low profile.

[0057] It is another object of the present invention to provide for aplating system which may be at least in part bioresorbable.

[0058] It is another object of the present invention to provide for aplating system comprising at least in part of bone ingrowth materialsand surfaces.

[0059] It is another object of the present invention to provide for aplating system comprising at least in part of bone growth promotingsubstances.

[0060] It is another object of the present invention to provide plateswith an improved holding ability within the bone due to a locked screwto plate crossover configuration.

[0061] It is another object of the present invention to provide a lockedplating system capable of selected and specific screw motion so as toaccommodate shortening of the bones to be joined.

[0062] It is another object of the present invention is to provide meansfor preventing distraction pseudoarthrosis of the anterior cervicalspine, while providing for cervical lordosis.

[0063] The above and other objects and features of the invention willbecome more readily apparent from the following description of preferredembodiments of the invention, provided with reference to theaccompanying drawings, which illustrate embodiments of the inventionsolely by way of non-limiting example.

BRIEF DESCRIPTION OF THE DRAWINGS

[0064]FIG. 1 is a perspective view of the first embodiment of a multiplelocking plate.

[0065]FIG. 2 is a top plan view of the multiple locking plate shown inFIG. 1.

[0066]FIG. 3 is a side view of the multiple locking plate shown in FIG.1.

[0067]FIG. 4 is an end view of the multiple locking plate shown in FIG.1.

[0068]FIG. 5 is a bottom view of the multiple locking plate shown inFIG. 1.

[0069]FIG. 6 is a top view of the multiple locking plate shown in FIGS.1-5, with locking elements installed, in an open configuration.

[0070]FIG. 7 is a top view of a modification of a plate of FIGS. 1-6with a four bone screw locking element in place.

[0071]FIG. 8 is a top view of a further embodiment of the multiplelocking plate of FIG. 1 with an elongated central slot for increasedcompression capability.

[0072]FIG. 9 is a locking element capable of use with the plates ofFIGS. 1-6.

[0073]FIG. 10 is a top view of a locking element for use with thecentral opening of the plate of FIGS. 7 and 22.

[0074]FIG. 11 is a top view of a locking cap for use in the end openingsshown in FIGS. 1, 6 and 7.

[0075]FIG. 12 is a side view of the locking element of FIG. 16.

[0076]FIG. 13 is a side view of another embodiment of the lockingelement of FIG. 16.

[0077]FIG. 14 is a perspective view of an alternative embodiment ofcervical spine locking plate using locking rivets.

[0078]FIG. 15 is a bottom view of the multiple locking plate of FIG. 14.

[0079]FIG. 16 is a top view of a preinstallable two bone screw lockingelement.

[0080]FIG. 17 is a top view of an alternative embodiment of a four bonescrew locking element having head slots for increased flexibility of thelocking tabs.

[0081]FIG. 18 is a bottom view of the rivet type locking element for usewith the central opening of the plate of FIG. 14.

[0082]FIG. 19 is a side view of a rivet locking element.

[0083]FIG. 20 is a top perspective view of the bottom portion of thehead of rivet of FIG. 19 viewed along lines 20-20.

[0084]FIG. 21 is a top perspective view of the head portion of a threebone screw locking element.

[0085]FIG. 22 is a perspective view of a multiple locking plate formedto utilize locking elements in the form of threaded caps.

[0086]FIG. 23 is a side view of a locking element for use with the plateof FIG. 22.

[0087]FIG. 24 is a side view of a bone screw.

[0088]FIG. 25 is a side view of an alternative form of a bone screw.

[0089]FIG. 26 is a bottom view of the bone screws shown in FIG. 24.

[0090]FIG. 27 is a top view of the bone screw shown in FIG. 24.

[0091]FIG. 28 is a top perspective view of a fourth embodiment of amultiple locking plate.

[0092]FIG. 29 is a perspective view of locking element for use with theplate of FIG. 28.

[0093]FIG. 30A is a partial side sectional view of the plate of FIG. 28along lines 30-30 with a bone screw in place.

[0094]FIG. 30B is an alternative embodiment of the bone screw of thepresent invention.

[0095]FIGS. 31A-31E illustrates top plan views of alternativeembodiments of the multiple locking elements of the present invention.

[0096]FIG. 32A is an elevational, cross-sectional detail view of aportion of the bone forming device engaged to a portion of the plate ofthe present invention.

[0097]FIG. 32B is an alternative embodiment showing a cross-sectionalview through the plate with a drill guide to guide a hole forminginstrument.

[0098]FIG. 32C is an elevational, cross-sectional detail view of aportion of an alternative embodiment of a bone forming device engaged toa portion of the plate of the present invention.

[0099]FIG. 32D is a cross-sectional view along line 32D-32D of FIG. 32C.

[0100]FIG. 33 is a perspective view showing the locking of the bonescrews to the plate.

[0101]FIG. 34A is a partial side sectional view of a shielded lockingelement attached to a driver instrument.

[0102]FIG. 34B is a partial side sectional view of an alternativeembodiment of a locking element.

[0103]FIG. 35 is a partial side sectional view of another embodiment ofthe locking element.

[0104]FIG. 36 is a partial cross-sectional view showing a plate, lockingelement and bone screws along lines 36-36 of FIG. 33.

[0105]FIG. 37 is an enlarged portion of detail along line 37 of FIG. 36.

[0106]FIG. 38 is a side partial cross sectional view of a plate holderattached to a plate.

[0107]FIG. 39A is a side partial cross sectional view of anotherembodiment of a plate holder attached to a plate.

[0108]FIG. 39B is a side partial cross sectional view of anotherembodiment of a plate holder attached to a plate.

[0109]FIG. 39C is an end view of the plate holder shown in FIG. 39B.

[0110]FIG. 39D is an enlarged fragmentation view of the tip of the plateholder shown in FIG. 39B.

[0111]FIG. 40 is a top perspective view of an embodiment of a singlelocking plate.

[0112]FIG. 41 is a top plan view of the plate shown in FIG. 40.

[0113]FIG. 42 is a side view of the plate shown in FIG. 40.

[0114]FIG. 43A is an end view of the plate shown in FIG. 40.

[0115]FIG. 43B is an end view of another embodiment of the plate shownin FIG. 40.

[0116]FIG. 44 is a bottom plan view of the plate shown in FIG. 40.

[0117]FIG. 45 is a top plan view of the plate shown in FIG. 40, withlocking elements in place.

[0118]FIG. 46 is a side view of a bone screw used with the plate shownin FIG. 40.

[0119]FIG. 47 is a top view of the bone screw shown in FIG. 46.

[0120]FIG. 48 is a bottom view of the bone screw of FIG. 46.

[0121]FIG. 49 is a top view of a locking cap for use with the singlelocking plate of FIG. 40.

[0122]FIG. 50 is a side view of the locking cap shown in FIG. 49.

[0123]FIG. 51 is a bottom view of the locking cap shown in FIGS. 49 and50.

[0124]FIG. 52 is a bottom perspective view of the locking cap of FIGS.49-51.

[0125]FIG. 53 is a cutaway view of the hole forming instrument threadedto a bone screw hole of a plate.

[0126]FIG. 54 is a perspective side sectional view of a drill and drillguide threadably engaged to the plate for drilling the hole forinsertion of a bone screw.

[0127]FIG. 55 is a perspective view of a single locking plate installedalong a bone with locking caps installed in two bone screw receivingholes.

[0128]FIG. 56 is a partial cross sectional view of a locking cap engagedto a driver for installing the locking cap.

[0129]FIG. 57 is a partial cross sectional view of the plate, bonescrews and locking cap of FIG. 55.

[0130]FIG. 58 is an enlarged fragmentary view of area 58 of FIG. 57.

[0131]FIG. 59 is a perspective view of a second embodiment of a singlelocking plate having individual locking elements to lock each bonescrew.

[0132]FIG. 60 is a perspective view of a threaded locking element foruse with the single locking plate of FIG. 59.

[0133]FIG. 61 is a partial side sectional view of the plate of FIG. 59viewed along lines 73-73 with the locking element of FIG. 60 in place tohold a bone screw, but not fully tightened.

[0134]FIG. 62 is a perspective view of an alternative locking elementfor use with a first modification of the single locking plate of FIG.59.

[0135]FIG. 63 is a side sectional view of the first modification of theplate of FIG. 59 with the locking element of FIG. 62.

[0136]FIG. 64 is a perspective view of an alternative locking elementfor use with the first modification of the plate of FIG. 59.

[0137]FIG. 65 is a side sectional view of the first modification of theplate of FIG. 59 with the locking element of FIG. 64 in place.

[0138]FIG. 66 is a perspective view of another alternative lockingelement in the form of a rivet for use with a second modification of thelocking plate of FIG. 59.

[0139]FIG. 67 is a partial side sectional detail view of the plate ofFIG. 59 modified to use a locking element of FIG. 66 shown in place.

[0140]FIG. 68 is a top plan view of a single-lock plate.

[0141]FIG. 69A is a top plan view of plate of a single-lock the presentinvention having a staggered screw hole pattern to provide crossing overof the bone screws into bone.

[0142]FIG. 69B is an alternative embodiment of the plate shown in FIG.69A.

[0143]FIG. 70A is cross sectional view of a bone with the plate of FIG.69A or 69B engaged to the bone with two bone screws shown crossed overand penetrating the bone in different planes.

[0144]FIGS. 70B-70D are end views of alternative embodiments of theplate shown in FIG. 70A.

[0145]FIG. 70E is a side elevational view of a plate in accordance withthe present invention shown applied to a long bone.

[0146]FIG. 70F is an enlarged detailed view along line 70F of FIG. 70E.

[0147]FIG. 71 is a top plan view of a further embodiment of the multiplelocking plate for use in stabilizing multiple segments of the spine orportions of a long bone.

[0148]FIGS. 72A-72H are top plan view of various embodiments of multiplelocking plates of the present invention.

[0149]FIG. 73 is a top plan view of an alternative embodiment of thepresent invention in the form of a multiple locking segmentable plateshown in a separated state.

[0150]FIG. 74 is a top plan view of an alternative embodiment of amultiple locking segmentable plate of FIG. 73 shown in a separatedstate.

[0151]FIG. 75 is a top plan view of an alternative embodiment of amultiple locking segmentable plate shown in an unseparated state.

[0152]FIG. 76 is a top plan view of an alternative embodiment of amultiple locking segmentable plate shown in an unseparated state.

[0153]FIG. 77 is a top plan view of a portion of an alternativeembodiment of a multiple locking segmentable plate shown in anunseparated state.

[0154]FIG. 78 is a top plan view of an alternative embodiment of amultiple locking segmentable plate shown in an unseparated state.

[0155]FIG. 79 is a top plan view of the multiple locking segmentableplate of FIG. 78 shown in a separated state.

[0156]FIG. 80 is a top plan view of an alternative embodiment of thepresent invention in the form of a single-lock segmentable plate shownin an unseparated state.

[0157]FIG. 81 is a top plan view of the single-lock segmentable plate ofFIG. 80 shown in a separated state.

[0158]FIG. 82 is a partial side sectional view of a passive dynamicscrew-plate-lock system of the present invention.

[0159]FIG. 83 is a top plan view of an opening in the plate shown inFIG. 82.

[0160]FIG. 84 is a partial side sectional view of the passive dynamicscrew-plate-lock system of FIG. 82 indicating motion in response to aforce being applied to the screw in the direction of Arrow A.

[0161]FIG. 85 is a partial side sectional view of the self-compressingscrew-plate-lock system of the present invention with the lock partiallyinserted.

[0162]FIG. 86 is a partial side sectional view of the self-compressingscrew-plate-lock system of FIG. 85 in with the lock fully inserted andthe screw seated.

[0163]FIG. 87 is a top plan view and opening in the plate shown in FIG.86.

[0164]FIG. 88 is a side sectional view of the opening in the plate shownin FIG. 87.

[0165]FIG. 89 is a partial side sectional view of an active dynamicscrew-plate-lock system of the present invention.

[0166]FIG. 90 is a top plan view of the opening in the plate shown inFIG. 89.

[0167]FIG. 91 is a top perspective view of the Belville type washer ofthe active dynamic screw-plate-lock system of FIG. 89.

[0168]FIG. 92 is a partial side sectional view of the active dynamicscrew-plate-lock system of FIG. 82 with the lock further tightened andthe screw seated.

[0169]FIG. 93 is a top perspective view of an alternative embodiment ofthe washer of FIG. 94 having a tab for insertion into a correspondingrecess in the plate.

[0170]FIG. 94 is a partial side sectional view of the active dynamicscrew-plate-lock system of FIG. 93 with the lock fully inserted, thescrew seated, and the tab of the washer inserted into a correspondingrecess in the plate.

[0171]FIG. 95A is a side perspective view of an alternative embodimentof a plate in accordance with the present invention.

[0172]FIG. 95B is a top perspective view of the plate in FIG. 95A.

[0173]FIG. 95C is a bottom perspective view of the plate in FIG. 95A.

[0174]FIG. 95D is a top perspective view of another embodiment of theplate of FIG. 95A.

[0175]FIG. 96A is a side perspective view of an alternative embodimentof a plate in accordance with the present invention.

[0176]FIG. 96B is a top perspective view of the plate in FIG. 96A.

[0177]FIG. 96C is a bottom perspective view of the plate in FIG. 96A.

[0178]FIG. 97A is a side perspective view of an alternative embodimentof a plate in accordance with the present invention.

[0179]FIG. 97B is a top perspective view of the plate in FIG. 97A.

[0180]FIG. 97C is a bottom perspective view of the plate in FIG. 97B.

[0181]FIG. 97D is a bottom plan view of the plate in FIG. 97B.

DETAILED DESCRIPTION OF THE DRAWINGS

[0182] In a first embodiment of the present invention a plurality ofbone screws are locked to a plate with a pre-installed locking element.This is referred to as the multiple locking plate system. The multiplelocking plates will be described, then the locking elements for lockingthe bone screws to the plate, and then novel bone screws for use withthe plates of the present invention. In an alternative embodiment, asingle locking element locks a single bone screw to the plate and isreferred to as the single lock system.

[0183] It is appreciated that the features associated with each of theembodiments of the present invention are not limited to the particularembodiment for which the features are described and are combinable withfeatures described in association with all the embodiments of thepresent invention.

[0184] 1. General Use Skeletal Plating-System

[0185] a. Multiple Locking Plate System

[0186] The preferred embodiment of the multiple locking plate 2according to the present invention is shown in FIGS. 1-5. Plate 2 has agenerally elongated form whose outline is generally rectangular. It isrecognized that other shapes for plate 2 may be employed. Plate 2 has abottom surface 27 for placement against bone portions, wherein asubstantial portion of bottom surface 27 is either flat or convex alongthe longitudinal axis of the plate. Plate 2 is for general skeletal useother than in the anterior cervical spine.

[0187] As an example only, plate 2 is provided with three locking screwholes 12, each of which in the preferred embodiment is internallythreaded 3, and each of which is surrounded by a shallow countersunkregion 14. As will be described in greater detail below, in thepreferred embodiment, bone screws are inserted in the bone screwreceiving holes and a single locking element associated with each of thelocking screw holes 12 locks a number of bone screws 30 in position atone time. The locking element may be pre-installed to the plate.

[0188] In the embodiment illustrated in FIGS. 1-5, each end lockingelement 20 will lock three bone screws 30 in place, while locking screw21 in central locking hole 12 locks two bone screws 30 in place. Asshown in FIG. 7, central locking element 25 can also be configured sothat four bone screws 30 are locked at one time. Plate 2 may have athickness appropriate for the strength required for the bone or bones towhich it is to be applied and generally in a range from 2 to 8 mm ispreferred.

[0189] As shown in FIG. 5, at least a portion of bottom surface 27 ofplate 2, preferably has a porous, and/or textured surface and may becoated with, impregnated with, or comprise of fusion promotingsubstances (such as bone morphogenetic proteins) so as to encourage thegrowth of bone along the underside of plate 2 from bone portion to boneportion. The textured bottom surface 27 also provides a medium forretaining fusion promoting substances with which the bottom surface 27layer can be impregnated prior to installation. The bottom surface 27 ofplate 2 may be given the desired porous textured form by rough blastingor any other conventional technology, such as etching, plasma spraying,sintering, and casting for example. If porous so as to promote boneingrowth, the bottom surface 27 is formed to have a porosity or poresize in the order of 50-500 microns, and preferably 100-300 microns.Bone growth promoting substances with which the porous, textured bottomsurface 27 can be impregnated include, but are not limited to, bonemorphogenetic proteins, hydroxyapatite, or hydroxyapatite tricalciumphosphate. The plate 2 may comprise of at least in part a resorbablematerial which can further be impregnated with a bone growth material sothat as the resorbable material is resorbed by the body of the patient,the bone growth material is released, thus acting as a time releasemechanism. By having plate 2 itself made from a material that isresorbable and by having bone growth promoting material present permitsthe bone portions to be joined to do so in a more natural manner as theplate becomes progressively less load bearing thereby avoiding latestress shielding of that bone area.

[0190] As further shown in FIGS. 4 and 5, at least one end of plate 2may have a recess 18 that can cooperate with a compression apparatus.

[0191]FIG. 6 is a top plan view of plate 2 of FIG. 1 with lockingelements 20, 21 inserted. In the preferred embodiment the lockingelements are in the form of screws that cooperate with the threadedinterior 3 of the locking holes 12. Each of these locking elements 20,21 is shown in its initial open orientation, where the orientation ofthe cutouts 22 in the head 23 of each locking element 20, 21 is orientedso as to permit introduction of bone screws 30 into adjacent bone screwreceiving holes 6,8 without interference by the head 23 of the lockingelement 20, 21.

[0192]FIG. 8 is a top view of another embodiment of plate 2 of FIGS.1-5, and is generally referred to as plate 120. Plate 120 is providedwith a longitudinally extending elongated slot 122 along itslongitudinal axis which is superimposed on the middle locking hole 12.Elongated slot 122 allows additional relative movement between plate 120and a compression post 54 associated with a compression tool during acompression procedure.

[0193] Referring to FIGS. 14 and 15, an alternative embodiment of amultiple locking plate referred to by the number 70 is shown. In plate70, rather than the threaded locking hole 12, a central opening 200 forreceiving a removable rivet 202, of the type shown in FIGS. 17-20, isprovided. FIG. 15 is a bottom view of the plate 70 shown in FIG. 14. Thecontour of plate 70 is the same as that of plate 2 shown in FIGS. 1-5.The rivet 202 is removable and fits within the unthreaded opening 200,comparable to the locking hole 12 and slot 122 described above. Otherembodiments may employ a rivet that is not removable, but ismanufactured as part of plate 70 as would be used in the end lockingholes 19 of FIGS. 14 and 15.

[0194] Referring to FIG. 22, another alternative embodiment of amultiple locking plate is shown and is generally referred to by thenumber 230. The plate 230 uses threaded caps, such as cap 300 shown inFIGS. 9 and 23, for a locking element or preferably one with cut outs asdescribed herein having an appearance in a top view such as the lockingscrew element in FIGS. 10-11, for example. The central locking hole 602has an elongated slot 234 for providing an increased compressioncapability, if desired.

[0195] Referring to FIGS. 10-13, a first embodiment of locking elements20, 21, and 25 in the form of locking screws according to the presentinvention for use with plate 2 are shown. FIG. 10 is a top plan viewillustrating the head 23 of the central locking element 25 shown in FIG.7. The shaft 46 of locking element 25 is threaded 47 to mate with thethreading 3 within the associated locking hole 12 of plate 2. As shownin FIG. 21, each segment 49 on each side of cutouts 22 of the lockingelement 21 has a bearing surface 48 formed at the lower surface oflocking element head 23. As shown in FIG. 16, the locking element head23 can be provided with two slits 42 for providing flexibility to thelocking element head 23 to assist in the locking element's ability toride over the top of the bone screw head 32 during the locking actionwhen the locking element is rotated.

[0196] Referring to FIGS. 6 and 10-13, it will be appreciated that whenthe locking elements 20, 21 are rotated in the clockwise direction withrespect to the view of FIG. 6, a respective bearing surface 48 will rideupon the curved top surface 39 of a respective bone screw head 32 inorder to positively lock the associated bone screws 30 and the lockingelements 20, 21 in place. This bearing feature can be used with theother locking elements described herein. Similarly, the bearing surfaceof the locking elements 20, 21, 25 can be also cammed.

[0197] Alternatively, as shown in FIGS. 12 and 13, in place of a flatbearing surface 48, a ramp or wedge shaped surface 44 may be used toincrease the force applied to the bone screw head 32. In an alternativeembodiment cam design when locked, the leading end of the ramped portion44 of locking element 21 would be lower than the prominence of the bonescrew head 32 so that more force is needed to lift the locking element21 and untighten it than is needed for the locking element 21 to remaintight and locked. However, the locking element head 23 need not haveslits, be cammed or have a ramped surface to achieve the locking of bonescrew 30 in place. Pressure, friction, interference fits, or otherengagement means capable of preventing the locking element from movingfrom its locked position may be employed.

[0198] Referring to FIGS. 17-20 a rivet 202 intended for use inassociation with plate 70 of FIGS. 14-15, is shown and is also shown indetail in cross section in FIGS. 19 and 20. Rivet 202 has a head 204, ashaft 206, and an elongated bottom segment 208 for fitting within thecorresponding opening 200 in plate 70. The lower surface 210 of the head204 of the rivet 202 has a bearing surface, such as on the bottom oflocking element 20, 21, for engaging the top surface 39 of the bonescrew head 32. For use in the end locking holes 19, the upper surface ofthe elongated bottom segment 208 can have a camming surface forcooperating with the camming surface 17 of the bottom of plate 70 tohold the rivet 202 in the locked position against the bone screw head32, as shown in FIG. 15. While the rivet of FIG. 18 is a separate,removable component from the plate, the rivets, and particularly thosefor use with the end locking holes, can be formed as part of the plateduring the manufacturing process of the plate and rivet can be nonremovable if so desired. The bearing surface of the rivet 202 may alsobe cammed to prevent the rivet from unlocking once the cammed portionpasses over the screw head.

[0199] Each of the above embodiments provides tight attachment of thelocking element relative the bone screw 30 and relevant plate.

[0200] In the alternative embodiment of multiple locking plate 23 shownin FIG. 22, the locking element can be in the form of threaded lockingcap 300 shown in FIG. 23. The threaded locking cap 300 has a thread 302on its outer circumference corresponding to the thread 303 on the innercircumference of the locking element depressions 304 in the top of plate230 shown in FIG. 22. The locking cap 300 is relatively thin,particularly compared to its width. The top 305 of locking cap 300 maybe provided with a noncircular recess or through hole 306 for receivinga similarly configured driving tool or employ other tool engaging means.

[0201] Referring to FIGS. 28, 29, and 30A another embodiment of themultiple locking plate generally referred to by the number 400 and alocking element in the form of a thin locking member 412 are shown.Plate 400 has an opening in its top surface for insertion of the thinlocking member 412, a recess 402 associated with each of the bone screwreceiving holes 408 and a slot 410 in the side wall of the bone screwreceiving holes 408 to permit the thin locking member 412, having aseries of thin projections or blades 414, thinner than the slot 410,that give this locking member 412 an appearance similar to that of apropeller. The thin locking member 412 is able to be rotated within theplate so as to not cover the bone screw holes, thus allowing the thinlocking member 412 to be pre-installed prior to the installation of thebone screws by the surgeon. Limited rotation of the thin locking member412 allows the blades 414 to protrude through the slot 410 and to covera portion of the top of the associated bone screws 30. The blades 414 ofthe thin locking member 412 are flexible and, when rotated, slide overthe top surface 39 of the bone screw head 32 to lock the bone screw 30in place. As with the other embodiments discussed, each of theembodiments of the locking element is capable of locking more than onebone screw 30. It is appreciated that the various multiple lockingplates and locking element combinations are capable of locking as manyas four bone screws at once, but are equally effective for locking alesser number or none at all, that is securing itself to the plate.

[0202] It will be noted that one characteristic of each of the abovedescribed locking element embodiments is to have a driver engagementmeans, in these cases for example, a recess 24 as large as the recess 34in the bone screws 30 so that the same tool can be used to turn both thebone screws 30 and the locking elements. Also, the locking elements aresufficiently strong and have sufficient mass so as to be able towithstand being locked without breakage.

[0203] Referring to FIG. 30B an alternative embodiment of the bone screw30 of the present invention is shown. Bone screw 30′ is a variable anglescrew having a head 32′ with a rounded top and has neck below the head32′ with relieved portions 33′a and 33′b to allow universal motion ofthe bone screw 30′ within the bone screw receiving hole of a plate asthe relieved portions provide clearance for the screw to move. In oneembodiment, bone screw 30′ may be secured to the plate by a lockingelement that prevents the screw from backing out, but allows the lockingelement to bear down on the top of the screw head 32′ still moverelative to the plate. Alternatively, the bottom surface of the seat ofthe bone screw receiving hole and the bottom of the screw head 32′ maybe roughened to provide some resistance to movement of the screw head32′ within the bone screw receiving hole and/or the lock may bind thescrew head with sufficient force such that once the lock is tightened nomovement of the screw within the plate is possible.

[0204] The above-described examples of the multiple locking elementshave a number of cutout portions having an arc with a radius greaterthan that of the bone screw head. However, it is appreciated thatpreinstallable multiple locking elements can have a configurationwithout any cutout portions and still permit for clearance of the bonescrew head. Some examples of such locking elements are shown in FIGS.31A-31D in which alternative embodiments of locking elements 20 a-20 dwithout cutout portions and in which the bone screws can be installedinto the bone screw receiving hole 6 even when the locking element ispre-installed to the plate. The locking elements may be rotated in thedirection of arrow A to bear upon at least a portion of the screw headto lock the bone screws to the plate.

[0205] In addition, the head 23 of each locking element 20, 21 isprovided at its center with a noncircular recess 24, such as shown inFIG. 9 which is engageable by an appropriate manipulation tool, such asshown in FIGS. 33-35. In the embodiment of head 23 shown in FIG. 9, theassociated tool would have a hex head, it is appreciated that othershapes of recesses in the head 23 may be used or other male or femaledriver engaging means may be used without departing from the scope ofthe present invention. The thread of each locking hole 12 and of eachlocking element 20, 21 has a close tolerance so that they will reliablyretain their orientations so as to permit introduction of bone screws 30into bone screw receiving holes 6, 8 without interference.Alternatively, the threads can be slightly mismatched or a thread orthreads can be made irregular or imperfect.

[0206] It is appreciated that while various forms of locking elementshave been disclosed, in light of the teaching, other equivalent meanscan be used for the purpose of locking the bone screws 30 in place. InFIG. 71, an alternative multiple locking plate 990 is shown havingadditional intermediate bone screw receiving holes 980 and, associatedlocking elements 960 for locking the bone screws 30 in place.

[0207] In FIGS. 72A-72H various plates 700 a-h are shown. Each of theseplates 700 a-h have bone screws inserted through the bone screwreceiving holes 6 and then locked in place. As shown in FIGS. 72A-72H,one locking element 710, or two locking elements can be used to lockfour bone screws in place. In FIGS. 72A-72H, each of plates 700 a-h isshown with the locking elements in their open orientation, before beingrotated to lock the bone screws. Plates 700 a-700 h each have lockingelements 710 for locking bone screws inserted into bone screw receivinghole 6 of the plate.

[0208]FIG. 24 provides a side view of one embodiment of a bone screw 30according to the present invention. Bone screw 30 has a bone screw head32, a shaft 33, and a tip 36. FIG. 27 is a top view of the bone screw30. At the center of bone screw head 32 is a profiled recess 34 whichmay have the same form as the recess 24 of each locking element 20, 21in which case it may be turned with the same tool as that employed forturning locking elements 20, 21. It is appreciated that the driverengaging portion of the bone screw 30 could be slotted, and be eithermale or female.

[0209] In the embodiment of bone screw 30 shown in FIG. 24, the bonescrew head 32 is stepped, with the first lower head portion 35 beingcontiguous with the screw shank 33 and has a smaller diameter than theupper portion of the bone screw head 32. Preferably, but withoutlimitation, when this embodiment of bone screw 30 is employed, each bonescrew receiving hole 6, 8 of plate 2 has a countersunk region 14matching the diameter of the upper portion of the bone screw head 32 anddimensioned for an interference fit. The lower portion 35 of the bonescrew head 32 is dimensioned to achieve an interference fit with itsassociated portion of bone screw receiving holes 6, 8. The largerdiameter upper portion of bone screw head 32 assures that the bone screw30 cannot be advanced completely through bone screw receiving holes 6, 8of plate 2. The bone screw 30 passes completely through the uppersurface of plate 2 without engaging the upper surface in any way.

[0210] As shown in FIG. 37, preferably, but without limitation, the head32 of screw 30 passes unobstructed through the upper surface of theplate until the lower surface of enlarged screw head 32 engages theupper face of the narrowed bone screw receiving portion at themidsubstance or below the midsubstance of the plate. This is consideredoptimal for allowing for the greatest screw to plate stability, evenabsent the lock, against all forces except those reverse the path ofinsertion, while still providing for the greatest plate strength beneaththe bone screw head 23. A sheer vertical circumferential wall is bestable to constrain the motion of a screw, if the head is similarlyconfigured and there is little tolerance between them. Placing thesupport of the head near the mid thickness of the plate is preferred asit allows the upper head to remain large to accommodate the recess forthe driver without being weakened, while placing the support of the headaway from the upper surface of the plate allows the screw head to bedeep into the plate. Placing the support of the head at approximatelythe mid thickness of the plate assures plenty of plate material beneaththe head to support while providing adequate head length above and belowthe contact point to prevent the contact point from acting as a fulcrumby providing adequate lever arms to prevent unwanted motion.

[0211] In the alternative embodiment of bone screw 30′, as shown in FIG.25, bone screw head 32′ is tapered in the direction from the top of thebone screw head 32′ toward screw tip 36′. Again, the bone screw head 32′is dimensioned to achieve an interference fit in the associated bonescrew receiving hole 6,8 when the bone screw 30′ has been fullyinstalled. When this embodiment of bone screw 30′ is employed, bonescrew receiving holes 6, 8 need not be provided with a countersunkregion 14.

[0212] In each of the above embodiments of the bone screws, the bonescrews 30 and 30′ present a unique combination of a tapered screw shaft33 and a helical thread 31. The diameter of screw shaft 33 generallyincreases from a distal portion of the shaft near the screw tip 36toward proximal portion of the shaft near screw head 32. In thepreferred embodiment, the rate of increase in diameter is also greaternear the bone screw head 32. Such a shape avoids stress risers andprovides increased strength to the screw at the screw-plate junction,where it is needed the most. The tapering of screw shaft 33 may have aconcave form, as shown in FIG. 24, or may be linear. The distal portionof the screw shaft 33 may assume a constant diameter.

[0213] The thread 31 of the bone screw 30 has a substantially constantouter, or crest, diameter “d” from below the bone screw head 32 to nearthe bone screw tip 36. In the screw tip 36, the crest diameter of thread31 may be reduced for preferably one to two turns to facilitate theinsertion and penetration of the bone screw 30 into the bone.

[0214] In the preferred embodiment, the thread 31 of each bone screw 30has an outer diameter slightly smaller than the diameter of the lowestportion 35 of the bone screw head 32, which is adjacent the trailing, orupper, end of the associated thread 31. In addition, the thread 31 isrelatively thin, in the direction of the longitudinal axis of the screw,and tapers outwardly, and has a cross section of a triangle, though thesides need not be straight.

[0215] As shown in FIG. 38, plate holder 870 has a hollow tubularhousing 872, with a central rod 874 having a thread 878 at one end forengaging one of the threaded locking holes 12 in plate 2. The bottom endof the housing 872 has projections 880, 882 that extend outwardly andthen downwardly to fit into the bone screw receiving holes 8 of plate 2preventing the housing 872 from rotating. The central rod 874 is locatedin the housing 872 such that it can be rotated by rotating a handle (notshown) which is fixed to the central rod 874 at its upper end.

[0216] In FIG. 39A an alternative embodiment of the plate holder 890 isshown. A single solid member 890 has a threaded projection 894 at itsbottom end for attachment to the central threaded locking hole 12 in theplate. The bottom surface of the holder 890 of this embodiment iscontoured so as to match the contours of the top surface of the plateadjacent to the locking hole 12, shown as a depression 14.

[0217] Referring to FIG. 39B-39D, an alternative embodiment of the plateholder 890′ is shown. Plate holder 890′ has a hollow tubular housing872′ having a handle 891′ at its top end and a bottom end 873′configured for insertion into a bone screw receiving holes 6 of a plate.A rod 874′ having a sharp tip 875′ is contained within housing 872′ andis spring biased by a spring 875′. A lever 893′ is provided foradvancing rod 874′ from within housing 872′. Lever 893′ has a cammedportion 892′ to lock rod 874′ in position.

[0218] The bottom end of the housing 872 is slitted to form projections880, 881, 882, and 883′ that are moved outwardly by the shaft of rod872′ above tip 875′ in the direction indicated by arrow A when rod 874′is advanced from within housing 872′ to engage and lock into the bonescrew receiving holes 6 of plate 2 preventing the housing 872′ fromseparating from plate 2. In this manner the plate holder 890′ functionsas both a holder for a plate and also as a temporary plate fixationdevice to hold the plate in the correct position to the bone prior tothe insertion of the bone screws. Further, holder 890′ can be used toform pilot holes for screw insertion into the bone portions.

[0219] Certain structural features of hole forming apparatus 60 areshown in greater detail in FIG. 32A. In particular, it can be seen thatthe bottom end of housing 62 has a projecting portion 69 dimensioned tofit precisely in a bone screw receiving hole 6 or 8 of plate 2. Thebottom 71 of the projecting portion 69 is flat in a plane perpendicularto the axis of housing 62. When the projecting portion 69 of housing 62is snugly inserted into a bone screw receiving hole 6, 8 and the flatbottom 71 is placed flush against the upper surface of plate 2, it isassured that the leading end 66 of shaft 64 will form a pilot hole inthe vertebral bone having an axis perpendicular to the plane of theassociated portion of plate 2, thereby assuring that the bone screw 30will be subsequently installed so that its axis is also perpendicular tothe plane which is parallel to the upper and lower surfaces of theassociated portion of plate 2.

[0220] When a plate is used which has a threaded bone screw receivinghole, the lower end of the pilot hole forming apparatus 60 is threadedso as to engage the thread in the bone screw receiving hole 6, 8 therebyfixing the plate and the pilot hole forming apparatus together, assuringa stable fit between the pilot hole forming apparatus and plate 2. Itshould be noted that the diameter of the leading end 66 of the shaft 64is small since it has to fit within the small space left between theinside wall of the pilot hole forming apparatus. Since it is only apilot hole for a self tapping bone screw 30 that is being formed, thesmall diameter is satisfactory.

[0221] Referring to FIG. 32B, if for any reason it should be desired toform the pilot hole in the bone 50 by drilling, rather than by the useof the pilot hole forming apparatus 60, use can be made of a drill guide80, having a lower end as shown in FIG. 32B. The drill 80 guide consistsof a tubular member 82 and a small diameter lower end 84 which isdimensioned to achieve a precise interference fit in the associated bonescrew receiving hole 6, 8 of plate 2. Along the small diameter lower end84, drill guide 80 has an axial end surface in a plane perpendicular tothe longitudinal axis of the drill guide 80 so that when the smalldiameter portion 84 is fitted into the bone screw receiving hole 6 andthe surface surrounding the small diameter portion 84 is flush againstthe upper surface of plate 2, the axis of the drill guiding bore 86 indrill guide 80 will be precisely perpendicular to the upper and lowersurfaces of the associated portion of plate 2. As with the casedescribed above, the bottom end of the drill guide 80 can be threaded soas to engage to the threaded opening of plate 2.

[0222] Referring to FIGS. 32C and 32D, an alternative embodiment of holeforming apparatus 60′ is shown. Hole forming apparatus 60′ is similar tohole forming apparatus 60, except that it has a ball end 62′ that fitswithin bone screw receiving hole 6. As shown in FIG. 32D, the ball end62′ may be oriented at any angle relative to the plate for angular holeformation into the bone. Hole forming apparatus 60′ provides forvariable angle preparation of the pilot holes for the bone screwsrelative to the plate.

[0223] After the bone screw receiving holes 6, 8 are formed in the bone50 through the upper two bone screw securing holes 6 of plate 2 by meansof either hole forming apparatus 60 or drill guide 80, bone screws 30are threaded into the bone 50 while holding plate 2 firmly against thebone 50 with plate holder 800.

[0224]FIG. 33 is a perspective view showing plate 2 of FIGS. 1-5, at astage of a surgical procedure when bone screws 30 have been fullyinstalled in bones or pieces of the same bone, and locking screws 20, 21have been rotated to lock three bone screws 30 in place; the left-handlocking screw 20 as viewed has been rotated through an angle of about45° to lock three bone screws 30 in place and the central lockingelement 21 has been rotated through an angle of about 90° to lock twoother bone screws 30 in place. At this time, one of the bearing surfaces44 of each locking element 20, 21 rests atop the screw head 32 of arespective bone screw 30. Ideally locking elements 20, 21 are providedto the user almost fully tightened, but in the open position such thatbone screws can be inserted. Full locking of the bone screw requires 90°or less of turning of the locking element and often 45° will suffice tolock the bone screws.

[0225] Installation of the multilock locking element 300 can also beperformed with a tool 220 such as shown in FIGS. 34A and 35 having asuitably shaped tip 222 with a length corresponding to the depth of hole306 in a locking cap 300. The end 222 of tool 220 is flared justproximal to the most distal end so that it creates a friction fit withthe screw cap 300 for ease of manipulation, and prevents the lockingelement 300 from falling off the tool 200. As shown in FIG. 34B, in thealternative, the tool receiving hole 306 can be flared to cooperativelyengage a tool having a tip with a corresponding configuration.

[0226]FIG. 36 is a cross-sectional view in the plane of the center ofthe two end locking screw holes 6 of plate 2, with two bone screws 30 intheir installed positions and locking element 21 in its lockingposition. FIG. 37 is an enlarged view of one of the bone screws 30 inplate 2 of FIG. 36. In a preferred embodiment, the axis of each screw 30is generally perpendicular to tangents to the upper and lower surfacesof plate 2 at points which are intersected by the longitudinal axis ofthe associated bone screw 30. Thus, because of the curvature of plate 2in the plane of FIG. 36, bone screws 30 can be directed so as toconverge toward one another at a desired angle. The axis of the two bonescrews 30 shown in FIG. 36 may subtend an angle sufficient to cause thepaths of bone screws in the same plate to cross within the substance ofthe bone. Alternatively, the curvature of the plate from side to sidemay be so as to conform to the surface of the bone to which the plate isbeing applied and the axis of the paired screw hole may deviate frombeing perpendicular to the plate when viewed on end to achieve theoptimal convergence.

[0227] Because the bone screws 30, once inserted, are locked to theplate, a “claw” of a rigid triangular frame structure is obtained ateach pair of bone screws 30 such that the attachment of plate 2 to thebone would be highly secure due to the trapping of a wedged mass of bonematerial between the angled bone screws, even if any thread strippingshould occur. The “claw” may be further formed by three angled bonescrews in a tripod configuration or by four bone screws in a four sidedclaw configuration.

[0228] b. Single-Lock Plate Systems

[0229] Another embodiment of the present invention, the single lockingplate system will now be described. FIGS. 40-45 are views of a firstembodiment of a single locking plate system generally referred to by thenumeral 600. Plate 600 has the same contour as plate 2 shown in FIGS.1-5. Plate 600 has a bottom surface 27 for placement against boneportions, wherein a substantial portion of bottom surface 27 is eitherflat and/or convex along the longitudinal axis of the plate though alesser portion of bottom surface 27 may be otherwise configured. Asshown in FIG. 43B, in another embodiment plate 600′ has a bottom surface627′ that is substantially flat along the transverse axis of plate 600′.

[0230] In a preferred embodiment, plate 600 contains bone screwreceiving holes 602 which are internally threaded 603 for receivingcorresponding locking elements in the form of a locking cap 610, shownin FIGS. 49-52. For example, in plate 600, the bone screw hole 602 mayhave an outer diameter appropriate to the screw diameter appropriate tothe bone(s) for which the plating system is to be applied. By way ofexample only, for use on a long bone such as the humerus, a bone screwof a diameter of 4.0 to 6.5 mm would be used and generally the screwhead would be slightly larger in diameter. If a threaded locking capwere to be used then allowing for the space occupied by the cap isthreads, the opening in the upper plate surface to receive the lockingcap would be similar to generally 0.2 mm to 4.0 mm greater than thescrew head size which could be 0.2 mm to 6 mm larger in diameter thanthe threaded shaft diameter of the bone screw of approximately 5 mm witha preferred range of 4-6 mm though possibly greater. Cap attaching meansother than threads may be used, such as bayonet type attachmentelements.

[0231] The bottom of each bone screw receiving hole 602 of plate 600 hasan inwardly stepped portion of properly selected dimensions forretaining an associated bone screw 170, as shown in FIGS. 46-48. Asdescribed in greater detail below, in this embodiment, a single lockingelement in the form of a locking cap 610 having threads 608 shown inFIGS. 49-52, is associated with each of the bone screws receiving holes602.

[0232] The difference between the bone screw 170 used in the singlelocking embodiment of the plate from the bone screw used in associationwith the multiple locking plate is essentially due to the fact thatwhereas in the multiple locking plate embodiment the locking elementsslide over a portion of the top 39 of the screw head 32 by a pressing,camming, or ramp action, in the single locking embodiment the lockingcap 610 presses directly on the head 172 of the bone screw 170.Therefore, the head 172 of the bone screw 170 of the present embodimentneed not be smooth.

[0233]FIG. 55 shows two bone screws 170 and associated threaded lockingcaps 610 in their fully installed positions. In these positions, headportions 174 and 176 of each bone screw 170 form an interference fitwith corresponding portions of an associated bone screw receiving hole602. Rim 612 of each threaded locking cap 610 forms an interference fitwith upper portion 178 of the head of its associated bone screw 170.Because the thread 608 of each locking cap 610 mates precisely with theinternal thread in an associated bone screw receiving hole 602, eachthreaded locking cap 610 is additionally subjected to a clamping forcebetween associated head portion 178 and the internal threads 603 ofassociated bone screw receiving hole 602. Preferably the rounded head614 of each threaded locking cap 610 assures that the upper surface ofan assembled plating system will be free of sharp edges, or projections.

[0234]FIG. 45 is a top plan view of the plate 600 partially installed,with threaded locking caps 600 installed in bone screw receiving holes602.

[0235]FIGS. 47-49 show a bone screw 170 for use with the single lockingplating system according to the invention. Bone screw 170 differs frombone screw 30 previously described in detail, only with regard to thestepped configuration of head 172. Preferably, bone screw 170 includes alower portion 174 which is contiguous with the screw shank and has areduced diameter equal to the maximum diameter of the shank 176. Portion178 of head 172 also has smaller diameter than lower portion 174. Thethread 182 has the same configuration as for the bone screw 30 discussedabove. However, either embodiment of bone screws can be used with any ofthe plates.

[0236] As in the case of the multiple locking plating system describedabove, the bone screws 170 for use in the single locking plating systemare preferably solid, where the screws adjoin the lower plate surface,where as some screws used with prior art plates are hollow and are proneto breakage, the only recess in the heads of the present inventionscrews being for engagement of the tip 222 of driving tool 220 and withthe recess being above the critical area of the lower plate surfacescrew junction. Therefore, these bone screws 170 remain robust. Thescrew heads are not deeply slifted into portions as per some prior artscrews and the locking caps do not impose a radial outer force to expandthe bone screw heads, so again the screw heads of the present inventionare not spread apart and stressed and weakened, and so remain robust. Itis appreciated that variable angle screws 30′ shown in FIG. 30B may beused in association with the single-lock plating system of the presentinvention.

[0237] Referring to FIGS. 59, 61 and 63 another alternative embodimentof the plate system of the present invention is shown and referred to bythe number 500. The plate 500 may have any contour as any of the platesof the present invention appropriate for skeletal use and in which asubstantial portion of the lower surface of the plate is either flat orconvex along the longitudinal axis of the plate. Associated with each ofthe bone screw openings 502, are threaded openings 524 offset from thebone screw openings 502 for receiving the locking element 506, 508,shown in FIGS. 60 and 62 as a threaded locking set screw or cap 506 orscrew 508. Alternatively, locking element 506 may have a cutout portionwith a radius greater than the radius of a bone screw head as is shownin connection with locking element 508 in FIG. 64.

[0238] It is appreciated that other configurations of single lockingplates may be employed.

[0239] Referring to FIGS. 64-67 the heads 507 and 526 of the lockingelements 508 and 522 have a recess 510 and 524 corresponding to theradius of the bone screw openings 502 and 528 so that the lockingelement 508 and 522 may be installed in place prior to the insertion ofthe bone screw 170 into the bone screw receiving hole 502 and 528. Whenthe locking elements 508 and 522 are rotated, a portion of its headextends over the top of the head of bone screw 170 to lock it in place.As with the above embodiments, the bottom surface of the locking screws508 and 522 can have a ramped, cammed, or other configuration forengagement with at least a portion of the screw head.

[0240] Referring to FIG. 68, a locking plate 900 is shown in which thereare a number of bone screw receiving holes 950 along the longitudinalaxis of plate 900. With plate 900 of FIG. 68, the close spacing andincreased number of bone screw receiving holes permits the surgeon tolocate appropriate holes to be aligned with each of the bone portions tobe fixated, as well as allowing for more points of fixation to the bone.

[0241] 2. Crossing Screw Plating System

[0242] Referring to FIG. 69A, an alternative embodiment of the plate ofthe present invention is shown and generally referred to by the numeral960. The plate 960 has multiple bone screw receiving holes 970 passingthrough plate 960. The bone screw receiving holes 970 are spaced apartin a staggered configuration such that the center point of each of thebone screw receiving holes 970 are on transverse lines that are offsetfrom one another. The center point of the bone screw receiving holes 970are also offset from the midline of plate 970, but with lesslongitudinal distance between one another, while providing forsufficient distance between holes 970 to assure plate strength, thanplate 900 shown in FIG. 68.

[0243] Referring to FIG. 69B, an alternative embodiment of plate 960 isshown and generally referred to by the numeral 960′. Plate 960′ has thesame staggered pattern of bone screw holes 970 as plate 960 to permitcrossing over of two bone screws 30. In addition, plate 960′ has anoverall configuration suitable for use in the spine including theanterior cervical spine. For such use, an embodiment could have openings910 in lobed portions at the corner of plate 960′ and recesses 930 foruse with a compressing apparatus. Plate 960 could have additional pairsof lobes along the plate length. It is appreciated that the overallconfiguration of plate 960′ can vary as can the offset pattern of thebone screw holes.

[0244] As shown in FIG. 70A, the offset pattern of bone screw receivingholes 970 permits longer bone screws 30 to be used than would otherwisebe possible if the screws were aligned in transverse pairs withouthaving bone screws 30 touch each other, due to the fact that the bonescrews 30 are in different planes, and each bone screw 30 gets to travela much longer diagonal path in crossing the sagittal midline, providinggreater fixation.

[0245] In the preferred embodiment of plate 960, the shafts of two bonescrews 30 cross over in close proximity to each other and define anincluded angle IA preferably between 25 to 90 degrees. Such a crossedconfiguration of bone screws 30 provides an extremely stable engagementof plate 960 to the bone as they are diagonally crossed within the samebone, thus trapping an area of bone between them.

[0246] For example, as shown in FIGS. 70B-70D, end views of alternativeembodiments of plate 960′ are shown wherein the bottom surface of theplate may be in the transverse plane relatively flat, curved, orotherwise configured to fit the surface configuration of the bone orbones to which the plate is to be applied. As shown in FIGS. 70E and70F, plates 960′ overall are generally shaped to conform to the bone(s)B to which they are applied.

[0247] 3. Segmentable Plating System

[0248] Referring to FIG. 73, a further embodiment of the presentinvention in the form of a segmentable plate generally referred to bythe number 1000 is shown in an separated state. Segmentable plate 1000has an elongated body with a plurality of bone screw receiving holes1010 spaced apart along a substantial portion of the length of thesegmentable plate 1000. Segmentable plate 1000 has a multiple lockingsystem 1020 for locking bone screws to plate 1010 as described above inconnection with multi-lock plate 2 shown in FIGS. 1-7. Plate 1000 ispreferably, but not limited to being made of a malleable material, suchas titanium or one of its surgically acceptable alloys.

[0249] Plate 1000 comprises a plurality of segments 1030-1038 which canbe separated from each other. A first segment 1030 of plate 1000 ismarked by a segmentation zone 1040 along which the plate may beseparated to separate first segment 1030 from the remainder of plate1000. Segmentation zone 1040 can be any type of scoring which creates aplace of least resistance along which when the plate 1000 is bentsufficiently to create a separation in the material of plate 1000, theseparation will occur along the segmentation zone. By way of exampleonly, in an anterior cervical plate having a thickness of 3 mmsegmentation zone 1040 may be formed by removing approximately 0.25 mmto 0.5 mm of material in total from the upper surface, lower surface orboth upper and low plate surfaces combined of the plate. The scoring canbe relatively thicker or thinner in width, variable in depth and ofvariable shape (e.g. “V” notched, rounded, etc.) to achieve the desiredqualities.

[0250] If plate 1000 is made of titanium, the inherent qualities oftitanium are such that the plate may be separated simply by bending theplate sufficiently along segmentation zone 1040 while supporting theplate with appropriate plate holders to either side of segmentation zone1040 and then bending the plate towards its original position at whichtime the plate will separate apart along the segmentation zone 1040,providing a sufficiently clean edge suitable for surgical use.

[0251] In use in the cervical spine as few as, only four differentsegmentable plates 1000 may be required to cover the wide range ofdifferent longitudinal spacing distances between bone screw receivingholes 1010 for application to one to four levels of the cervical spine.For example, a set of four segmentable plates 1000 to cover the variouscombinations required for application to one to four levels of thecervical spine would include a first segmentable plate having a firstsegment with a spacing distance between the bone screw receiving holesof 10 mm, and subsequent segments similarly spaced at 10 mm intervalsbetween the holes; a second segmentable plate having a first segmentwith a spacing distance between the bone screw receiving holes of 12.5mm, and subsequent segments spaced at 12.5 mm intervals between thescrew holes; a third segmentable plate having a first segment with aspacing distance between the bone screw receiving holes of 15 mm andsubsequent segments spaced apart at 15 mm intervals between the holes;and a fourth segmentable plate having a first segment with a spacingdistance between the bone screw receiving holes of 17.5 mm andsubsequent segments spaced apart at 17.5 mm intervals between the holes.

[0252] The longitudinal spacing between the bone screw receiving holes1010 may be varied by changing the length of the portion of plate 1000between bone screw receiving holes 1010 as illustrated by the dottedlines in FIG. 74.

[0253] While the described plates may be separable into a multitude ofusable portions, as would be desirable for manufacturing purposes andpossibly for clinical use, because of regulatory issues involving theidentification of each implant with a distinct and singular implantidentification number for tracking purposes it may be desirable toconfigure the plates of the present invention such that each plate willyield only one usable portion. In order to accomplish this goal, thesegmentation zone 1040 is made as shown in FIG. 79, such that theunused, separated pieces of the segmentable plates would not be usableas plates and would be discarded.

[0254] The ability to separate a plate into segments also providessignificant advantages in the manufacturing process. By way of example,in the process of investment casting, a process commonly used to produceplates, the cost of the material is not as significant as the laborinvolved in the manufacturing. Therefore, the manufacturer can cast onelong segmentable plate which can then be separated in the latermanufacturing stages to yield multiple plates at an overall lower cost.Similarly, if the plate were in the alternative to be manufactured bymachining from solid stock, great labor could be saved by fixturing andsecuring a single long plate that is later separable into multipleplates rather than having to fixture and secure each of those platesindividually.

[0255] Referring to FIGS. 75-79, various segmentable plates 1300-1700are shown for application in reconstructive surgery. Plates 1300-1700have bone screw receiving holes 1310-1710, locking elements 1320-1720,and separation zones 1340-1740 respectively. For example, during repairof a broken eye socket, the segmentable plates 1300-1700 can be used toalign and maintain the broken bone portions in correct spatialrelationship. The curved characteristics of an eye socket would requirethe plate used to repair the socket to match the curvature. Thesegmentable plates 1300-1700 are made of a malleable metal, themalleability of which is enhanced by the segmentation of the plate, andcan be easily contoured by the surgeon to the appropriate curvature. Thecorrect length of the segmentable plate can also be easily be selectedby the surgeon by separating the plate at the appropriate segment asdescribed above in connection with plate 1000 shown in FIG. 73.

[0256] It should be noted that if for example surgical titanium alloy isselected for the plate material, then the separation zones allow theplate to be more easily bent, but without separating. The presentinvention makes a virtue of the material property of that alloy in thatit may be bent without damage, but fails with surprisingly little forceif first bent and then bent back. Back bending is therefore only donefor plate separation and is not needed for contouring which requiresonly primary bending.

[0257] Referring to FIGS. 80 and 81, alternative embodiments of thesegmentable plate are shown and generally referred to by the numeral1800 and 1900. Plates 1800-1900 having locking elements 1820 that areinserted into bone screw receiving holes 1810 and correspond to thesingle lock plate configuration described above in connection with FIGS.40-49. Segmentable plates 1800-1900 may be segmented at segmentationzones 1840 and 1940 as described above in connection with the multiplelock embodiment of the segmentation plate 1000.

[0258] 4. Combination Screw-Lock-Plating System

[0259] a. Passive Dynamic

[0260] Referring to FIGS. 82-84 the passive dynamic system 2000 is shownhaving a plate with a screw hole 2010 passing through the top and bottomsurfaces of the plate 2020 for receiving a bone screw 2030. The screwhole 2010 has a round opening 2040 at the top of the plate 2020 and anopening 2050 in the bottom of the plate that is in part coaxial with thetop opening 2040, but extends in one direction to form an oblong. Therounded head 2032 of bone screw 2030 is prevented from backing out ofplate 2020 with a locking element 2060 that is engaged to plate 2020,while the shaft of bone screw 2030 is capable of angular motion in thedirection of arrow A relative to plate 2020, since there is space in theoblong-shaped bottom opening 2040 of the screw hole 2010 for the shaftof the bone screw 2030 to travel in the one permitted direction relativeto the plate 2020.

[0261] The passive dynamic system allows bone screw 2030 to moverelative to plate 2020 even after being locked to plate when a force ispresented against the screw. This system does not cause screw movement,but only allows for movement of the screw to occur and this is a“passive” system. Nevertheless, screw 2030 retains the ability to resistany unwanted motion in all other directions. The use of variable screw30′ as already described may also allow for passive dynamic action, butis not generally preferred as it does not limit the motion to but asingle direction.

[0262] b. Self-Compressing

[0263] Referring to FIGS. 85-88, a self-compressing system 2100 is showncomprising a plate 2120 having a bone screw receiving 2110 hole with atop opening 2140 that is preferably but not necessarily round, andhaving a rounded recessed portion 2142 is shown. The bone screwreceiving hole has bottom opening 2150 that is smaller in diameter thanthe top opening 2140 and has a central longitudinal axis 2153 that isoffset from the central longitudinal axis 2151 of the top opening 2140.The bone screw has a rounded head portion 2132 which fits within therounded bottom 2142 of the top opening 2140 and permits movement of thescrew head 2132 within the top opening in order to provide theappropriate angle A of the bone screw shaft with respect to the plate2120 as the bone screw shaft passes through the bottom opening 2150.

[0264] In the self-compressing system, as the bone screw 2130 is beinglocked to the plate 2120 with a locking element 2160, the lockingelement 2160 puts pressure on the bone screw head 2132 to make the bonescrew 2130 move in one direction. The bone screw 2130 cannot move backonce it is locked to the plate 2120 by the locking element 2160. Thepurpose of the self-compressing system 2100 is to provide a fixed andlocked angle A on the bone screw 2130 for providing compression of boneportions.

[0265] c. Active Dynamic

[0266] Referring to FIGS. 89-92, the active dynamic system 2200 of thepresent invention is shown comprising a screw 2230 that is mounted to aplate 2220 under a spring loaded force, such as with a Belville typewasher 2270 that applies a selected force to the screw 2230. The bonescrew 2230 will move in the direction of the force that is being appliedas bottom opening 2250 of the bone screw receiving hole is oblongshaped. For example, the big end 2272 of the spring formed by washer2270 bears down on the screw head 2232 away from the direction that thebone screw 2230 is to be moved. For any given use, (plate, screw, hole,and spring) it is simple to determine correct resistance, that being anamount less than would separate the bone.

[0267] Referring to FIGS. 93-94, the washer 2270 may also have a tab2290 which fits into a recess 2292 formed within the top opening inorder to facilitate proper orientation of the washer when placed withinthe opening or alternatively the washer 2270 may have a non-circularshape so as to not rotate when positioned.

[0268] In an active dynamic system, a pre-loaded force is applied to abone screw that keeps the screw in a certain orientation with respect tothe plate. The bone screw will only move further in the pre-orienteddirection if there is space available and if there is no opposing forcepresent to counteract the pre-loaded force on the screw. These teachingsmay be readily and beneficially combined so as to for example form asystem that compresses on full screw seating, continues to urge the boneportions together, and can permit still further shortenings.

[0269] Referring to FIGS. 95A-95D, an alternative embodiment of a plateof the present invention is shown and generally referred to by thenumeral 3000. Plate 3000 has a bottom surface 3027 that is convex alonga substantial portion of the longitudinal axis of the plate and isconcave along the transverse axis of the plate 3000. Plate 3000 has asingle-locking element 3022 for locking a single bone screw 3030 toplate 3000.

[0270] As shown in FIG. 95D, in another embodiment plate 3000′ has abottom surface 3027′ that is substantially flat along the transverseaxis of plate 3000′.

[0271] Referring to FIGS. 96A-96C, an alternative embodiment of a plateof the present invention is shown and generally referred to by thenumeral 3100. Plate 3100 has a bottom surface that is flat along asubstantial portion of the longitudinal axis of the plate and is concavealong the transverse axis of the plate. Plate 3100 has a multiplelocking element 3120 for locking two bone screws 3130 and single lockingelements 3122 for locking individual bone screws 3130 to plate 3100.Bone screw receiving holes 3140 are staggered such that the center pointof each of the bone screw receiving holes 3142 and 3144 are ontransverse lines that are offset from one another. The center point ofthe bone screw receiving holes 970 are also offset from the midline ofplate. The shafts of two bone screws 30 cross over in close proximity toeach other and define an included angle IA between 25 to 90 degrees.Such a crossed configuration of bone screws 30 provides an extremelystable engagement of plate 960 to the bone as they are very closetogether and diagonally crossed within the same bone, thus trapping anarea of bone between them.

[0272] Plate 3100 comprises a plurality of segments 3150-3156 which canbe separated from each other. A first segment 3150 of plate 3100 ismarked by segmentation zones 3160-3164 along which the plate may beseparated to separate segments 3150, 3152, 3154, or 3156 from theremainder of plate 3100. Segmentation zones 3160-3164 can be any type ofscoring which creates a place of least resistance along which when theplate 3100 is bent sufficiently to create a separation in the materialof plate 3100, the separation will occur along the segmentation zone.

[0273] It is appreciated that plate 3100 may include one or more of thescrew-lock-plating systems 2000, 2100, or 2200 described above in FIGS.82-84.

[0274] Referring to FIGS. 97A-97D, an alternative embodiment of a plateof the present invention is shown and generally referred to by thenumeral 3200. Plate 3200 has a bottom surface that is flat along asubstantial portion of the longitudinal axis of the plate and is concavealong the transverse axis of the plate and has an upper surface that isconcave along the transverse axis of the plate 3200.

[0275] As shown in FIG. 97D, plate 3000 may include one or more of thescrew-lock-plating systems 2000, 2100, or 2200 described above in FIGS.82-94.

[0276] While particular embodiments of the present invention have beenshown and described, it will be obvious to those skilled in the art thatchanges and modifications may be made without departing from thisinvention in its broader aspects and, therefore, the aim in the appendedclaims is to cover all such changes and modifications as fall within thetrue spirit and scope of this invention.

[0277] While specific innovative features may have been presented inreference to specific examples, they are just examples, and it should beunderstood that various combinations of these innovative features beyondthose specifically shown are taught such that they may now be easilyalternatively combined and are hereby anticipated and claimed.

What is claimed is:
 1. A spinal plating system, comprising: a plateincluding a first portion defining a first aperture and a second portiondefining a second aperture, said first and second portionsinterconnected by a mid-portion having a reduced lateral width relativeto said first and second portions to facilitate bending of said platealong said mid-portion; and at least two prongs extending from saidplate, one of said prongs positioned between said first and secondapertures adjacent said mid-portion.
 2. The spinal plating system ofclaim 1, wherein said plate has an hour glass shape.
 3. The spinalplating system of claim 1, wherein said plate defines a groove extendinglaterally across said plate between said first and second apertures tofacilitate bending of said plate along said mid-portion.
 4. The spinalplating system of claim 1, wherein said mid-portion is defined by atleast one inwardly extending notch.
 5. The spinal plating system ofclaim 4, wherein said mid-portion is defined by an opposing pair of saidinwardly extending notches.
 6. The spinal plating system of claim 1,wherein another of said prongs is positioned aside one of said first andsecond apertures opposite said mid-portion.